All the horses that beat Lazarus in Aus over the mile were also trained to race mostly longer distances and came from similar lead up campaigns. Although he did have probably the hardest lead up to Miracle Miles . I don't see any reason that they would not improve just as much if they were trained for only mile racing in faster carts and on faster tracks. It's just my opinion and unfortunately most of the horses that beat him have retired or broken down so we will probably never find out.
He is doing a great job promoting Australian harness racing to the world and hopefully he will break the world record.